Multilayer capacitor and installation structure of multilayer capacitor

ABSTRACT

In a multilayer capacitor, a multilayer capacitor main body includes first and second main surfaces, first and second side surfaces, and first and second end surfaces, the first and second main surfaces extending in a length direction and a width direction, the first and second side surfaces extending in the length direction and a thickness direction, and the first and second end surfaces extending in the width direction and the thickness direction. The second main surface is depressed in a portion extending from opposite ends of the second main surface toward a center of the second main surface in the length direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multilayer capacitor and aninstallation structure of the multilayer capacitor.

2. Description of the Related Art

A multilayer ceramic capacitor has been widely used as a capacitor whichhas small size and large capacitance. In the related art, a multilayerceramic capacitor with a substantially rectangular parallelepiped shape,for example, has been widely used. For example, Japanese UnexaminedPatent Application Publication No. 2013-46052 discloses a multilayerceramic capacitor with a substantially rectangular parallelepiped shapeincluding two main surfaces, two side surfaces and two end surfaces. Themultilayer ceramic capacitor disclosed in Japanese Unexamined PatentApplication Publication No. 2013-46052 includes first and second signalterminal electrodes and a grounding terminal electrode. The first andsecond signal terminal electrodes are respectively connected to aplurality of first inner electrodes, and the first signal terminalelectrode is provided on an end portion of one of the main surfaces onone side in a length direction. The second signal terminal electrode isprovided on the other end portion of the main surface on the other sidein the length direction. The grounding terminal electrode is connectedto a plurality of second inner electrodes. Each of the second electrodesfaces each of the first electrodes via a ceramic portion. The groundingterminal electrode is provided on a portion of the main surface betweenthe first signal terminal electrode and the second signal terminalelectrode in the length direction.

The multilayer capacitor, which includes the first and second signalterminal electrodes and the grounding terminal electrode provided on themain surface, as disclosed in Japanese Unexamined Patent ApplicationPublication No. 2013-46052 is required to have satisfactory electricalcharacteristics.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a multilayercapacitor with satisfactory electrical characteristics.

According to a first preferred embodiment of the present invention, amultilayer capacitor includes a multilayer capacitor main body whichincludes first and second main surfaces, first and second side surfaces,and first and second end surfaces, the first and second main surfacesextending in a length direction and a width direction, the first andsecond side surfaces extending in the length direction and a thicknessdirection, and the first and second end surfaces extending in the widthdirection and the thickness direction; a first inner electrode extendingin the length direction and the thickness direction and including afirst effective portion, a first extending portion, and a secondextending portion, the first extending portion being connected to thefirst effective portion and extending to the second main surface, andthe second extending portion being connected to the first effectiveportion and extending to the second main surface; a second innerelectrode extending in the length direction and the thickness directionand including a second effective portion and a third extending portion,the second effective portion facing the first effective portion in thewidth direction, and the third extending portion being connected to thesecond effective portion, not facing the first inner electrode, andextending to the second main surface; a first terminal electrode whichis connected to an exposed portion of the first extending portion andextends across a portion of the second main surface on a side of thefirst end surface in the length direction, the first end surface, andthe first and second side surfaces; a second terminal electrode which isconnected to an exposed portion of the second extending portion andextends across a portion of the second main surface on a side of thesecond end surface in the length direction, the second end surface, andthe first and second side surfaces; and a third terminal electrode whichis connected to an exposed portion of the third extending portion andextends across a portion of the second main surface between the firstterminal electrode and the second terminal electrode in the lengthdirection and the first and second side surfaces; wherein a distance inthe thickness direction between the first effective portion and thesecond main surface is shorter than a distance in the thicknessdirection between the first effective portion and the first mainsurface; and a distance in the thickness direction between the secondeffective portion and the second main surface is shorter than a distancein the thickness direction between the second effective portion and thefirst main surface.

It is preferable that the first effective portion includes a firstprojecting portion which projects toward the second main surface, and aminimum distance in the thickness direction between the first projectingportion and the second main surface is shorter than dimensions of thefirst and second extending portions, and that the second effectiveportion includes a second projecting portion which projects toward thesecond main surface, and a minimum distance in the thickness directionbetween the second projecting portion and the second main surface isshorter than a dimension in the thickness direction of the thirdextending portion.

It is preferable that a dimension of the third terminal electrode on thesecond main surface in the length direction is greater than a dimensionof the first and second terminal electrodes on the second main surfacein the length direction.

It is preferable that the first and second terminal electrodes extendacross the second main surface from a first end to a second end in thewidth direction and have a thickest portion at a portion on a side ofthe first end beyond a center portion in the width direction.

It is preferable that the thickest portion projects toward the centerportion in the length direction.

It is preferable that L1 represents a dimension of the exposed portionof the first extending portion in the length direction; L2 represents adimension of the exposed portion of the second extending portion in thelength direction; and L3 represents a dimension of the exposed portionof the third extending portion in the length direction; wherein L3>L1and L3>L2 are satisfied.

It is preferable that a distance in the length direction between thefirst end surface and the first extending portion at a center orapproximate center of the second main surface in the width direction issmaller than each distance in the length direction between the first endsurface and the first extending portion nearest to the first and secondside surfaces; and a distance in the length direction between the secondend surface and the second extending portion at a center or approximatecenter of the second main surface in the width direction is smaller thaneach distance in the length direction between the second end surface andthe second extending portion nearest to the first and second sidesurfaces.

It is preferable that the first main surface does not contain anyterminal electrodes thereon.

According to various preferred embodiments of the present invention,multilayer capacitors with satisfactory electrical characteristics areprovided.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a multilayer capacitoraccording to a first preferred embodiment of the present invention.

FIG. 2 is a schematic front view of a second side surface of themultilayer capacitor according to the first preferred embodiment of thepresent invention.

FIG. 3 is a schematic front view of a second end surface of themultilayer capacitor according to the first preferred embodiment of thepresent invention.

FIG. 4 is a schematic cross-sectional view taken along line IV-IV inFIG. 2.

FIG. 5 is a schematic cross-sectional view taken along line V-V in FIG.2.

FIG. 6 is a schematic cross-sectional view taken along line VI-VI inFIG. 2.

FIG. 7 is a schematic cross-sectional view taken along line VII-VII inFIG. 4.

FIG. 8 is a schematic cross-sectional view taken along line VIII-VIII inFIG. 4.

FIG. 9 is a schematic bottom view of the multilayer capacitor accordingto the first preferred embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view of an installation structureof the multilayer capacitor according to the first preferred embodimentof the present invention.

FIG. 11 is a schematic cross-sectional view of the installationstructure of the multilayer capacitor according to the first preferredembodiment of the present invention.

FIG. 12 is a schematic cross-sectional view of an installation structureof a multilayer capacitor according to a second preferred embodiment ofthe present invention.

FIG. 13 is a schematic cross-sectional view of the installationstructure of the multilayer capacitor according to the second preferredembodiment of the present invention.

FIG. 14 is a schematic perspective view of a multilayer capacitoraccording to a third preferred embodiment of the present invention.

FIG. 15 is a schematic cross-sectional view of the multilayer capacitoraccording to the third preferred embodiment of the present invention.

FIG. 16 is a schematic cross-sectional view of the multilayer capacitoraccording to the third preferred embodiment of the present invention.

FIG. 17 is a schematic cross-sectional view of the multilayer capacitoraccording to the third preferred embodiment of the present invention.

FIG. 18 is a schematic cross-sectional view of the multilayer capacitoraccording to the third preferred embodiment of the present invention.

FIG. 19 is a schematic perspective view of a multilayer capacitoraccording to a fourth preferred embodiment of the present invention.

FIG. 20 is a schematic front view of a second side surface of themultilayer capacitor according to the fourth preferred embodiment of thepresent invention.

FIG. 21 is a schematic cross-sectional view of an installation structureof the multilayer capacitor according to the fourth preferred embodimentof the present invention.

FIG. 22 is a schematic cross-sectional view illustrating a process offorming a terminal electrode.

FIG. 23 is a schematic cross-sectional view showing a portion of theterminal electrode.

FIG. 24 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a fifth preferred embodiment of the presentinvention.

FIG. 25 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a sixth preferred embodiment of the presentinvention.

FIG. 26 is a schematic cross-sectional view of the multilayer ceramiccapacitor according to the sixth preferred embodiment of the presentinvention.

FIG. 27 is a schematic cross-sectional view of a multilayer capacitoraccording to a seventh preferred embodiment of the present invention.

FIG. 28 is a schematic cross-sectional view of the multilayer capacitoraccording to the seventh preferred embodiment of the present invention.

FIG. 29 is a schematic back view of a multilayer ceramic capacitoraccording to an eighth preferred embodiment of the present invention.

FIG. 30 is a schematic cross-sectional view of an installation structureof a multilayer capacitor according to a ninth preferred embodiment ofthe present invention.

FIG. 31 is a schematic cross-sectional view of an installation structureof a multilayer capacitor according to a reference example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, examples of preferred embodiments of the present inventionwill be described. However, the following examples of preferredembodiments will be described only for an illustrative purpose. Thepresent invention is not limited to the examples of the followingpreferred embodiments.

In the respective drawings to be referred to in the description ofexamples of the preferred embodiments, the same reference numerals willbe given to members with the same or substantially the same functions.In addition, the drawings to be referred to in the description of thepreferred embodiments are schematically depicted. Dimension ratios ofobjects depicted in the drawings are different from actual dimensionratios of the objects in some cases. Between drawings, dimension ratiosof objects differ in some cases. Specific dimension ratios and the likeof the objects should be determined in consideration of the followingdescription.

FIG. 1 is a schematic perspective view of a multilayer capacitor 1according to a preferred embodiment of the present invention, whichincludes two main surfaces, two side surfaces and two edge surfaces.FIG. 2 is a schematic front view of a second side surface of themultilayer capacitor 1 according to the present preferred embodiment.FIG. 3 is a schematic front view of a second end surface of themultilayer capacitor 1 according to the present preferred embodiment.FIG. 4 is a schematic cross-sectional view taken along line IV-IV inFIG. 2. FIG. 5 is a schematic cross-sectional view taken along line V-Vin FIG. 2. FIG. 6 is a schematic cross-sectional view taken along lineVI-VI in FIG. 2. FIG. 7 is a schematic cross-sectional view taken alongline VII-VII in FIG. 4. FIG. 8 is a schematic cross-sectional view takenalong line VIII-VIII in FIG. 4. FIG. 9 is a schematic bottom view of themultilayer capacitor according to the first preferred embodiment. Inother words, FIG. 9 is a schematic front view of a second main surfaceof the multilayer capacitor 1 according to the first preferredembodiment.

As shown in FIGS. 1 to 6, a multilayer capacitor 1 is provided with amultilayer capacitor main body 10. The multilayer capacitor main body 10preferably has a rectangular or substantially rectangular parallelepipedshape. Corner portions and ridge portions of the multilayer capacitormain body 10 may be chamfered or rounded. In addition, convexities andconcavities may be provided on main surfaces and/or side surfaces.

The multilayer capacitor main body 10 includes first and second mainsurfaces 10 a and 10 b, first and second side surfaces 10 c and 10 d,and first and second end surfaces 10 e and 10 f. The first and secondmain surfaces 10 a and 10 b respectively extend in a width direction Wand a length direction L. The first and second side surfaces 10 c and 10d respectively extend in the width direction W and a thickness directionT. The first and second end surfaces 10 e and 10 f respectively extendin the length direction L and the thickness direction T. The lengthdirection L is orthogonal to the width direction. The thicknessdirection T is orthogonal to each of the length direction L and thewidth direction W.

A dimension of the multilayer capacitor 1 in the length direction L ispreferably from about 2.00 mm to about 2.10 mm, for example. A dimensionof the multilayer capacitor 1 in the thickness direction T is preferablyfrom about 0.7 mm to about 1.0 mm, for example. A dimension of themultilayer capacitor 1 in the width direction W is preferably from about1.20 mm to about 1.40 mm, for example.

In addition, the dimensions of the multilayer capacitor 1 in the lengthdirection L, the thickness direction T and the width direction W can bemeasured by using an easily accessible micrometer, for example, MDC-25MXmanufactured by Mitutoyo Corporation.

The multilayer capacitor main body 10 is made of appropriate ceramics inaccordance with functions of the multilayer capacitor 1. Specifically,the multilayer capacitor main body 10 can be formed of dielectricceramics, for example. Specific examples of the dielectric ceramicsinclude BaTiO₃, CaTiO₃, SrTiO₃, and CaZrO₃. An accessory component suchas an Mn compound, Mg compound, Si compound, Fe compound, Cr compound,Co compound, Ni compound, Al compound, V compound, or a rare earthcompound may be appropriately added to the multilayer capacitor mainbody 10 in accordance with characteristics required for the multilayercapacitor 1.

As shown in FIGS. 4 to 6, a plurality of first inner electrodes 11 and aplurality of second inner electrodes 12 are provided inside themultilayer capacitor main body 10. The first inner electrodes 11 and thesecond inner electrodes 12 are respectively provided in the lengthdirection L and the thickness direction T. The first inner electrodes 11and the second inner electrodes 12 are alternately provided atpredetermined intervals in the width direction W. A first innerelectrode 11 and a second inner electrode 12 which are adjacent to eachother in the width direction W face each other in the width direction Wvia a ceramic portion 10 g.

As shown in FIG. 7, each first inner electrode 11 extends to the firstand second main surfaces 10 a and 10 b, respectively. Specifically, eachfirst inner electrode 11 includes first to fourth extending portions 11a to 11 d. A portion of the first extending portion 11 a and a portionof the second extending portion 11 b are exposed at predeterminedportions of the first main surface 10 a. A portion of the thirdextending portion 11 c and a portion of the fourth extending portion 11d are exposed at predetermined portions of the second main surface 10 b.In other words, the first extending portion 11 a extends to a portion ofthe first main surface 10 a on an L(A) side in the length direction L.The second extending portion 11 b extends to a portion of the first mainsurface 10 on an L(B) side in the length direction L. The thirdextending portion 11 c extends to a portion of the second main surface10 b on the L(A) side in the length direction L. The fourth extendingportion 11 d extends to a portion of the second main surface 10 b on theL(B) side in the length direction L. Each first inner electrode 11 isspaced away from the first and second end surfaces 10 e and 10 f. Thatis, each first inner electrode 11 does not extend to the first andsecond end surfaces 10 e and 10 f. In other words, each first innerelectrode 11 preferably does not have any portions which are exposed atthe first and second end surfaces.

As shown in FIG. 8, each second inner electrode 12 extends to the firstand second main surfaces 10 a and 10 b, respectively. Specifically, eachsecond inner electrode 12 includes first and second extending portions12 a and 12 b.

A portion of the second extending portion 12 a is exposed at apredetermined portion of the first main surface 10 a. A portion of thesecond extending portion 12 b is exposed at a predetermined portion ofthe second main surface 10 b. In other words, the first extendingportion 12 a extends to a center portion of the first main surface 10 ain the length direction L. The second extending portion 12 b extends toa center portion of the second main surface 10 b in the length directionL. The first and second extending portions 12 a and 12 b and the firstto fourth extending portions 11 a to 11 d are configured so as not toface each other in the width direction W. Each second inner electrode 12is spaced away from the first and second end surfaces 10 e and 10 f.That is, each second inner electrode 12 does not extend to the first andsecond end surfaces 10 e and 10 f. In other words, each first innerelectrode 12 does not have any portions which are exposed at the firstand second end surfaces.

The first and second inner electrodes 11 and 12 can be configured ofmetal such as Ni, Cu, Ag, Pd, Au, or Ag—Pd alloy, for example.

As shown in FIGS. 1, 2, 7, and 8, first to third terminal electrodes 13to 15 are provided on the second main surface 10 b. According to thepresent preferred embodiment, the first terminal electrodes 13 and thesecond terminal electrode 14 respectively configure ground terminalelectrodes (negative terminal electrode). The third terminal electrode15 configures a signal terminal electrode (positive terminal electrode).

As shown in FIG. 1, the terminal electrode 13 is provided on a portionof the second main surface 10 b on a side of the first end surface 10 e(L(A) side) in the length direction L. The terminal electrode 13 extendsacross the second main surface 10 b from an end portion on one side toan end portion on the other side in the width direction W. The terminalelectrode 13 extends across the first and second side surfaces 10 c and10 d and the first end surface 10 c from the second main surface 10 b.The terminal electrode 13 includes a portion 13 a provided on the firstside surface 10 c, a portion 13 b provided on the second side surface 10d, and a portion 13 c provided on the first end surface 10 e. Theterminal electrode 13 does not reach the first main surface 10 a. Thatis, the portions 13 a to 13 c do not reach the first main surface 10 a.A length of the portions 13 a to 13 c in the thickness direction T ispreferably less than about ½ of a length of the multilayer capacitormain body 10 in the thickness direction T, and is more preferably equalto or less than about ⅓ of the length of the multilayer capacitor mainbody 10 in the thickness direction T, for example.

A dimension of the terminal electrode 13 in the length direction L ofthe second main surface is preferably from about 0.35 mm to about 0.45mm, for example.

As shown in FIGS. 5 and 7, the terminal electrode 13 is connected to thefirst inner electrodes 11. The terminal electrode 13 covers the exposedportion of the third extending portion 11 c of each first innerelectrode 11.

As shown in FIG. 1, the terminal electrode 14 is provided at a portionof the second main surface 10 b on a side of the second end surface 10 f(L(B) side) in the length direction L. The terminal electrode 14 extendsacross the second main surface 10 b from the end portion on one side tothe end portion on the other side in the width direction W. The terminalelectrode 14 extends across the first and second side surfaces 10 c and10 d and the second end surface 10 f from the second main surface 10 b.The terminal electrode 14 includes a portion 14 a provided on the firstside surface 10 c, a portion 14 b provided on the second side surface 10d, and a portion 14 c provided on the second end surface 10 f. Theterminal electrode 14 does not reach the first main surface 10 a. Thatis, the portions 14 a to 14 c do not reach the first main surface 10 a.A length of the portions 14 a to 14 c in the thickness direction T ispreferably less than about ½ of the length of the multilayer capacitormain body 10 in the thickness direction T, and is more preferably equalto or less than about ⅓ of the length of the multilayer capacitor mainbody 10 in the thickness direction T, for example.

A dimension of the terminal electrode 14 in the length direction L ofthe second main surface is preferably from about 0.35 mm to about 0.45mm, for example.

As shown in FIGS. 6 and 7, the terminal electrode 14 is connected to thefirst inner electrodes 11. The terminal electrode 14 covers the exposedportion of the fourth extending portion 11 d of each first innerelectrode 11.

As shown in FIG. 1, the terminal electrode 15 is provided at a portionof the second main surface 10 b between the terminal electrode 13 andthe terminal electrode 14 in the length direction L. The terminalelectrode 15 extends across the second main surface 10 b from the endportion on one side to the end portion on the other side in the widthdirection W. The terminal electrode 15 is spaced away from the terminalelectrodes 13 and 14. The terminal electrode 15 extends across the firstand second side surfaces 10 c and 10 d from the second main surface 10b. The terminal electrode 15 includes a portion 15 a positioned on thefirst side surface 10 c and a portion 15 b positioned on the second sidesurface 10 d. The terminal electrode 15 does not reach the first mainsurface 10 a. That is, a length of the portions 15 a and 15 b in thethickness direction T is preferably less than about ½ of the length ofthe multilayer capacitor main body 10 in the thickness direction T, andis more preferably equal to or less than about ⅓ of the length of themultilayer capacitor main body 10 in the thickness direction T, forexample.

A dimension of the terminal electrode 15 in the length direction L ofthe second main surface is preferably from about 0.63 mm to about 0.67mm, for example.

As shown in FIG. 8, the terminal electrode 15 is connected to the secondinner electrodes 12. The terminal electrode 15 covers the exposedportion of the second extending portion 12 b of each second innerelectrode 12.

In addition, dimensions of the terminal electrodes 13, 14, and 15 in thelength direction L of the second main surface can be measured bychecking the second main surface of the capacitor main body attwenty-fold magnification by using a measurement microscope MH-60manufactured by Nikon Corporation, for example. In this measurement, thelongest portion of each of the terminal electrodes 13, 14 and 15 in thelength direction L may be measured.

The terminal electrodes 16 to 18 are provided on the first main surface10 a. According to the present preferred embodiment, the terminalelectrodes 16 and 17 respectively configure grounding terminalelectrodes. The terminal electrode 18 configures a signal terminalelectrode.

As shown in FIG. 1, the terminal electrode 16 is provided at a portionof the first main surface 10 a on the side of the first end surface 10 e(L(A) side) in the length direction L. The terminal electrode 16 extendsacross the first main surface 10 a from an end portion on one side to anend portion on the other side in the width direction W. The terminalelectrode 16 extends across the first and second side surfaces 10 c and10 d and the first end surface 10 e from the first main surface 10 a.The terminal electrode 16 includes a portion 16 a provided on the firstside surface 10 c, a portion 16 b provided on the second side surface 10d, and a portion 16 c provided on the first end surface 10 e. Theterminal electrode 16 does not reach the second main surface 10 b. Thatis, the portions 16 a to 16 c do not reach the second main surface 10 b.A length of the portions 16 a to 16 c in the thickness direction T ispreferably less than about ½ of the length of the multilayer capacitormain body 10 in the thickness direction T, and is more preferably equalto or less than about ⅓ of the length of the multilayer capacitor mainbody 10 in the thickness direction T, for example.

As shown in FIGS. 5 and 7, the terminal electrode 16 is connected to thefirst inner electrodes 11. The terminal electrode 16 covers the exposedportion of the first extending portion 11 a of each first innerelectrode 11.

As shown in FIG. 1, the terminal electrode 17 is provided at a portionof the first main surface 10 a on the side of the second end surface 10f (L(B) side) in the length direction. The terminal electrode 17 extendsacross the first main surface 10 a from the end portion on one side tothe end portion on the other side in the width direction W. The terminalelectrode 17 extends across the first and second side surfaces 10 c and10 d and the second end surface 10 f from the first main surface 10 a.The terminal electrode 17 includes a portion 17 a provided on the firstside surface 10 c, a portion 17 b provided on the second side surface 10d, and a portion 17 c provided on the second end surface 10 f. Theterminal electrode 17 does not reach the second main surface 10 b. Thatis, the portions 17 a to 17 c do not reach the second main surface 10 b.A length of the portions 17 a to 17 c in the thickness direction T ispreferably less than about ½ of the length of the multilayer capacitormain body 10 in the thickness direction T, and is more preferably equalto or less than about ⅓ of the length of the multilayer capacitor mainbody 10 in the thickness direction T, for example.

As shown in FIGS. 6 and 7, the terminal electrode 17 is connected to thefirst inner electrodes 11. The terminal electrode 17 covers the exposedportion of the second extending portion 11 b of each first innerelectrode 11.

As shown in FIG. 1, the terminal electrode 18 is provided at a portionof the first main surface 10 a between the terminal electrode 16 and theterminal electrode 17 in the length direction L. The terminal electrode18 extends across the first main surface 10 a from the end portion onone side to the end portion on the other side in the width direction W.The terminal electrode 18 is spaced away from the terminal electrodes 16and 17. The terminal electrode 18 extends across the first and secondside surfaces 10 c and 10 d from the first main surface 10 a. Theterminal electrode 18 includes a portion 18 a positioned on the firstside surface 10 c and a portion 18 b positioned on the second sidesurface 10 d. The terminal electrode 18 does not reach the second mainsurface 10 b. That is, a length of the portions 18 a and 18 b in thethickness direction T is preferably less than about ½ of the length ofthe multilayer capacitor main body 10 in the thickness direction T, andis more preferably equal to or less than about ⅓ of the length of themultilayer capacitor main body 10 in the thickness direction T, forexample.

As shown in FIGS. 4 and 8, the terminal electrode 18 is connected to thesecond inner electrodes 12. The terminal electrode 18 covers the exposedportion of the first extending portion 12 a of each second innerelectrode 12.

The terminal electrodes 13 to 18 can be respectively configured ofappropriate metal such as Ni, Cu, Ag, Pd, Au, Sn, Cr, or Ag—Pd alloy,for example.

FIGS. 10 and 11 are schematic cross-sectional views of an installationstructure of the multilayer capacitor according to the present preferredembodiment. As shown in FIGS. 10 and 11, an installation structure 2 ofthe multilayer capacitor is provided with the multilayer capacitor 1 andan installation board 20. The multilayer capacitor 1 is installed on aninstallation surface 20 a of the installation board 20. The installationboard 20 includes first to third lands 21 to 23 provided on theinstallation surface 20 a.

The first land 21 is electrically connected to the terminal electrode13. The first land 21 extends to a farther outer side portion (L(A)side) than the terminal electrode 13 in the length direction L. That is,the first land 21 includes a portion which is positioned at an outerside portion of the multilayer capacitor 1 in a plan view (when viewedfrom the thickness direction T).

The second land 22 is electrically connected to the terminal electrode14. The second land 22 extends to a farther outer side portion (L(B)side) than the terminal electrode 14 in the length direction L. That is,the second land 22 includes a portion which is positioned at an outerside portion of the multilayer capacitor 1 in a plan view (when viewedfrom the thickness direction T).

The third land 23 is electrically connected to the terminal electrode15.

The lands 21 to 23 and the terminal electrodes 13 to 15 are joined toeach other by a conductive material 30 and are electrically connected toeach other. The conductive material 30 is not particularly limited aslong as the conductive material 30 exhibits a conductive property. Theconductive material 30 can be configured of a solder, for example.

The terminal electrodes can be formed by applying and baking conductivepaste, for example. When the conductive paste is applied from one end tothe other end in the width direction on the main surface, a centerportion of each terminal electrode in the width direction W is generallythickest due to influences of gravity force and surface tension. Forthis reason, the multilayer capacitor is inclined to one side or theother side in the width direction W by setting the center portion ofeach terminal electrode in the width direction W as a supporting pointwhen the multilayer capacitor is installed. Therefore, an installationposture of the multilayer capacitor varies. If the installation postureof the multilayer capacitor varies, there is a concern about variationof characteristics of the multilayer capacitor after the installationthereof.

As shown in FIGS. 4 to 6, the terminal electrodes 13 to 15 in themultilayer capacitor 1 respectively have the thickest portions on thesecond main surface 10 b on a W2 side in the width direction W.Therefore, the multilayer capacitor 1 is installed in a state where atotal of six points, namely the thickest portions 13 c 1, 14 c 1, and 15c 1 of the portions 13 d, 14 c, and 15 d, which are positioned on thesecond main surface 10 b, on the W2 side and the end portions of theterminal electrodes 13 to 15 on a W(A) side are in contact with theinstallation board 20 as shown in FIG. 11.

Therefore, the multilayer capacitor 1 may be tilted when it is installedon the installation board 20. Also, it is possible to reduce variationsin the installation posture of the multilayer capacitor 1. Accordingly,it is possible to significantly reduce or prevent variations in thecharacteristics of the multilayer capacitor 1 after the installation.

As for thicknesses of the terminal electrodes 13 to 15, cross sectionsof the terminal electrodes 13 to 15 are exposed by polishing from thefirst side surface 10 c of the multilayer capacitor 1 toward the centerof the width direction. It is possible to measure the thicknesses of theterminal electrodes 13 to 15 by removing sag caused by the polishing andthen observing the cross sections thereof by using a microscope.

In addition, a portion of the terminal electrode 15 with the largestthickness in the width direction W can be checked by measuring athickness of a cross section which appears after polishing themultilayer capacitor 1 from the first end surface 10 e or the second endsurface 10 f toward the terminal electrode 15, for example.

In addition, a portion of the first terminal electrode 13 with thelargest thickness in the width direction W can be checked by measuring athickness of a cross section which appears after polishing themultilayer capacitor 1 from the first end surface 10 e toward the firstterminal electrode 13, for example.

In addition, a portion of the second terminal electrode 14 with thelargest thickness in the width direction W can be checked by measuring athickness of a cross section which appears after polishing themultilayer capacitor 1 from the second end surface 10 f toward thesecond terminal electrode 14, for example.

Incidentally, it is preferable to set a current loop to be short from aviewpoint of reducing equivalent series inductance (ESL) of theinstalled multilayer capacitor 1. Therefore, it is preferable to set thewidths of the exposed portions of the extending portions 11 c, 11 d, and12 b in the length direction L to be wide. However, since distancesbetween the outer border of the terminal electrodes, the border betweenthe signal terminal electrode and the multilayer capacitor main body 10,to each of the extending portions decrease if the widths of the exposedportions of the extending portions 11 c, 11 d, and 12 b are widened,moisture easily enters the extending portions. Therefore, there is atendency in that moisture resistance deteriorates.

As a result of intensive study, the present inventors discovered that ina case where the inner electrodes 12 and the outer electrode 15 wereconnected to a positive pole and the inner electrodes 11 and the outerelectrodes 13 and 14 were connected to a negative pole, the moistureresistance did not easily deteriorate on the negative pole side even ifdistances from the outer borders of the terminal electrodes 13 and 14 tothe exposed portions of the extending portions 11 c and 11 d were shortwhile the moisture resistance deteriorated on the positive pole side ifa distance from the outer borders of the terminal electrode 15 to theexposed portions of the extending portion 12 b was short.

That is, since the multilayer capacitor 1 satisfies Equations (1) to(4), which are described in more detail below, it is possible tosignificantly reduce the ESL of the installed multilayer capacitor 1while maintaining excellent moisture resistance of the multilayercapacitor 1.

As shown in FIG. 7, L1 represents a dimension of the exposed portion ofthe third extending portion 11 c of at least one of the first innerelectrodes 11 in the length direction L.

As shown in FIG. 7, L(B) represents the dimension of the exposed portionof the fourth extending portion 11 d of at least one of the first innerelectrodes 11 in the length direction L.

As shown in FIG. 8, L3 represents a dimension of the exposed portion ofthe second extending portion 12 b of at least one of the second innerelectrodes 12 in the length direction L.

As shown in FIG. 7, L4 represents a distance in the length direction Lfrom an inner edge (right edge in FIG. 7) of the exposed portion of thethird extending portion 11 c of the at least one of the first innerelectrodes 11 to an inner edge (right edge in FIG. 7) of the portion 13d of the grounding terminal electrode 13 that covers the exposed portionof the extending portion 11 c. In this case, the inner edge of theexposed portion of the third extending portion 11 c and the inner edgeof the portion 13 d are the respective edges closest to the terminalelectrode 15.

As shown in FIG. 7, L5 represents a distance in the length direction Lfrom an inner edge (left edge in FIG. 7) of the exposed portion of thefourth extending portion 11 d of the at least one of the internalelectrodes 11 to the inner edge (left edge in FIG. 7) of the portion 14d of the grounding terminal electrode 14 that covers the exposed portionof the fourth extending portion 11 d. In this case, the inner edge ofthe exposed portion of the fourth extending portion 11 d and the inneredge of the portion 14 d are the respective edges closest to theterminal electrode 15.

As shown in FIG. 8, L6 represents a distance in the length direction Lfrom an edge (left edge in FIG. 8) of the exposed portion of the secondextending portion 12 b of the at least one of the internal electrodes 12to an edge (left edge in FIG. 8) of a portion 15 c of the groundingterminal electrode 15 that covers the exposed portion of the extendingportion 12 b. In this case, the edge of the exposed portion of thesecond extending portion 12 b and the edge of the portion 15 c are therespective edges closest to the terminal electrode 13.

As shown in FIG. 8, L7 represents a distance from an edge (right edge inFIG. 8) of the exposed portion of the second extending portion 12 b ofthe at least one of the internal electrodes 12 to an edge (right edge inFIG. 8) of the portion 15 c. In this case, the edge of the exposedportion of the second extending portion 12 b and the edge of the portion15 c are the respective edges closest to the terminal electrode 14.

Equations (1) to (4) preferably are as follows:L3>L1  (1)L3>L2  (2)L6>L4  (3)L7>L5  (4)

In addition, the reason that the moisture resistance does not easilydeteriorate on the side of the negative pole 11 even if the distancesfrom the inner edges of the terminal electrodes 13 and 14 to the inneredges of the exposed portions of the extending portions 11 c and 11 dare short while the moisture resistance deteriorates on the side of thepositive pole 12 if the distance from the left and right edges of theterminal electrode 15 to the left and right edges of the exposedportions of the extending portion 12 b is short can be considered asfollows. If water enters the inside of the multilayer capacitor, protons(H⁺) are generated as represented by the following Equation (5). Thereaction of Equation (5) occurs only on the positive side and does notoccur on the negative side. If protons generated at the positive polemove to the negative pole, then insulation resistance (IR) of themultilayer capacitor decreases.H₂O→H⁺+½O₂+2e ⁻  (5)

Therefore, if it is possible to significantly reduce or preventgeneration of protons at the positive pole, then it is possible tosignificantly reduced or prevent a decrease in insulation resistance(IR). For this reason, it is possible to improve the moisture resistanceof the multilayer capacitor. Accordingly, the moisture resistance doesnot deteriorate even if the distances from the inner edges of theterminal electrodes 13 and 14 to the inner edges of the extendingportions 11 c and 11 d are short and moisture can easily reach thenegative pole 11. In contrast, the moisture resistance deteriorates ifthe distance from the left and right edges of the terminal electrode 15to the left and right edges of the exposed portions of the extendingportion 12 b is short since moisture can easily reach the positive pole12.

Experimental Examples 1 to 4

Thirty six non-limiting examples of multilayer capacitors with the sameor substantially the same configuration as that of the multilayercapacitor 1 according to the above-described preferred embodiment wereproduced under the following conditions. A voltage of 4 V was applied tothe produced samples for 500 hours in an environment at a temperature of85° C. and a humidity of 85% RH. Thereafter, insulation resistance (IR)was measured. As a result, samples with log IR under about 10^(5.7) weredetermined to be defective products, and samples with log IR of equal toor greater than about 10^(5.7) were determined to be non-defectiveproducts. The results are shown in Table 1.

-   -   Size of multilayer capacitor: 2.0 mm (L)×1.25 mm (W)×0.7 mm (T)    -   Design Values    -   Ceramics: BaTiO₃    -   Capacitance: 47 μF    -   Rated voltage: 4 V    -   Configuration of terminal electrodes: first layer: Cu-fused        electrode, second layer; Ni-plated film, third layer: Sn-plated        film

TABLE 1 Number of events of IR deterioration/ L4, L5 L6, L7 L1, L2 ESLnumber (μm) (μm) (μm) L3 (μm) (pH) of samples Example 1 70 90 250 50047.0 0/36 Example 2 70 75 250 530 45.5 0/36 Comparative 70 10 250 50047.0 2/36 Example 1 Comparative 70 180 250 240 60.0 0/36 Example 2Comparative 70 160 250 230 60.5 0/36 Example 3

Based on the results shown in Table 1, it is possible to realize both adecrease in ESL and an improvement in reliability by satisfying L3>L1,L3>L2, L6>L4, and L7>L5, for example.

Incidentally, if the installation board 20 is bent in the lengthdirection L, stress concentrates on contact points (see FIG. 7, forexample) between the second main surface 10 b and the inner edges of theportions 13 d and 14 d of the terminal electrodes 13 and 14 in thelength direction L. Therefore, cracking easily occurs in the multilayercapacitor main body 10 from the contact points between the second mainsurface 10 b and the inner edges of the portions 13 d and 14 d of theterminal electrodes 13 and 14 in the length direction L as start points.

In the multilayer capacitor 1, portions of the terminal electrodes 13and 14 on at least the W2 side in the width direction W include portions13 d 2 and 14 d 2 which project toward the center of multilayercapacitor main body 10 along the length direction L as shown in FIG. 9.Therefore, the stress applied to the multilayer capacitor main body 10at the contact points between the tip end portions of the portions 13 dand 14 d and the second main surface 10 b when the installation board 20is bent in the length direction L is dispersed in the width direction W.For this reason, the stress does not easily concentrate on a specificportion or one location of the multilayer capacitor main body 10.Accordingly, cracking does not easily occur in the multilayer capacitormain body 10.

In addition, the terminal electrodes 13 and 14 according to the presentpreferred embodiment can be formed by applying conductive paste and thendrying ceramic element assemblies in a state of being inclined such thatthe W2 side is located at a lower side than the W(A) side in the widthdirection W, for example.

In addition, it is possible to form the terminal electrodes 13 and 14 tobe thicker than the terminal electrode 15 by setting the number of timesof the application of the conductive paste for the formation of theterminal electrodes 13 and 14 to be larger than the number of times ofthe application of the conductive paste for the formation of theterminal electrode 15.

As for the thicknesses of the terminal electrodes 13 to 15, crosssections thereof are exposed by polishing the multilayer ceramiccapacitor from the side surfaces to the center of the width directionuntil the width thereof becomes half. It is possible to measure thethicknesses by removing sag caused by the polishing and then observingthe cross sections.

If the terminal electrode 15 is thicker than the terminal electrodes 13and 14, the multilayer ceramic capacitor can be easily installed so asto be parallel or substantially parallel with the installation board.Therefore, it is possible to reduce the height of the multilayer ceramiccapacitor, which is installed on the installation board, in a normaldirection of the installation board.

In the following description, the terminal electrodes 13 to 18 will becollectively referred to as a terminal electrode 50 in some cases. Asshown in FIG. 23, the terminal electrode 50 is preferably configured asa multilayer body of a baked electrode layer 51, an Ni-plated film 52provided on the baked electrode layer 51, and an Sn-plated film 53provided on the Ni-plated film 52.

If the plated film 52 of each of the terminal electrodes 13 and 14 isthicker than the plated film 52 of the terminal electrode 15, aself-alignment effect by the terminal electrodes 13 and 14 is achieved.Therefore, the multilayer ceramic capacitor is not easily rotated aboutthe position of the terminal electrode 15, does not easily deviate froma desired installation position, and is capable of being stablyinstalled. Therefore, it is possible to connect the terminal electrodes13 and 14 to the lands of the installation board. According to themultilayer ceramic capacitor, it is thus possible to significantlyreduce or prevent an increase in the equivalent series inductance (ESL)after the installation on the installation board.

A thickness of the Ni-plated film 52 of the terminal electrode 15 ispreferably equal to or greater than about 2 μm and equal to or less thanabout 3 μm, and a thickness of the Sn-plated film is preferably equal toor greater than about 4 μm and equal to or less than about 5 μm, forexample. A total thickness of the plated films 52 and 53 of the terminalelectrode 15 is preferably equal to or greater than about 6 μm and equalto or less than about 8 μm, for example.

A thickness of the Ni-plated film 52 of each of the terminal electrodes13 and 14 is preferably equal to or greater than about 4 μm and equal toor less than about 5 μm, and a thickness of the Sn-plated film ispreferably equal to or greater than about 5 μm and equal to or less thanabout 6 μm, for example. A total thickness of the plated films 52 and 53of each of the terminal electrodes 13 and 14 is preferably equal to orgreater than about 9 μm and equal to or less than about 11 μm, forexample.

The Sn-plated film is not necessarily provided.

The thickness of the plated film may be measured by polishing the sidesurfaces of the multilayer ceramic capacitor in the width directionuntil the thickness of the multilayer capacitor main body 10 becomeshalf or about half and then observing a cross section obtained afterremoving polishing sag, for example.

Incidentally, stress is applied to the multilayer capacitor 1 when theinstallation board 20 is bent in the width direction W or during reflow.The stress applied to the multilayer capacitor 1 easily concentrates onportions of the capacitor main body 10 at which the portions 13 c and 14c of the terminal electrodes 13 and 14 positioned on the end surfaces 10e and 10 f are in contact with the end surfaces 10 e and 10 f.Therefore, cracking easily occurs in the capacitor main body 10 from theportions at which the portions 13 c and 14 c are in contact with the endsurfaces 10 e and 10 f.

In the multilayer capacitor 1, the portion 13 c of the terminalelectrode 13, which is positioned on the first end surface 10 e, and theportion 14 c of the terminal electrode 14, which is positioned on thesecond end surface 10 f, are positioned beyond a region where the firsteffective portion 11A and the second effective portion 12A face eachother in the width direction W. In other words, the length of theportion 13 c of the terminal electrode 13 provided on the first endsurface 10 e in the thickness direction T is longer than the length ofthe third extending portion 11 c in the thickness direction T. And thelength of the portion 14 c of the terminal electrode 14 provided on thesecond end surface 10 f in the thickness direction T is longer than thelength of the third extending portion 11 d in the thickness direction T.That is, the portions 13 c and 14 c are overlapped with the portion inwhich the first effective portion 11A and the second effective portion12A face each other in the width direction W, in the thickness directionT. Therefore, cracking does not easily occur in the capacitor main body10 from the portion where the portions 13 c and 14 c are in contact withthe end surfaces 10 e and 10 f. The reason will be considered asfollows.

During baking, the amount of contraction of the conductive paste layeris greater than the amount of contraction of a ceramic green sheet.Therefore, compression stress in a region where an amount of theconductive paste layer per unit volume is large relatively increases,and compression stress in a region where a presence rate of theconductive paste layer per unit area is low relatively decreases.Specifically, compression stress in a region where the extendingportions 11 c, 11 d, and 12 b is present in the thickness direction T isrelatively small, and compression stress in a region where the first andsecond effective portions 11A and 12A are present in the thicknessdirection T is relatively large. Therefore, if the portions where theportions 13 c and 14 c are in contact with the end surfaces 10 e and 10f are positioned in the region where the extending portions 11 c, 11 d,and 12 b are present in the thickness direction T, tension stress easilyoccurs at the portions where the portions 13 c and 14 c are in contactwith the end surfaces 10 e and 10 f. Therefore, cracking easily occurs.In contrast, if the portions where the portions 13 c and 14 c are incontact with the end surfaces 10 e and 10 f are positioned in the regionin which the first effective portion 11A and the second effectiveportion 12A face each other in the width direction W, and which haslarge compression stress, in the thickness direction T as in themultilayer capacitor 1, tension stress does not easily occur at theportions where the portions 13 c and 14 c are in contact with the endsurfaces 10 e and 10 f. Accordingly, cracking does not easily occur.

In addition, the positional relationship between the portions 13 c and14 c and the effective portions 11A and 12A can be checked by observinga cross section, which appears after polishing the multilayer ceramiccapacitor 1 from the first side surface or the second side surface inthe width direction, at twenty-fold magnification by using a measurementmicroscope MM-60 manufactured by Nikon Corporation, for example.

In addition, a length of each of the portions 13 c and 14 c in thethickness direction T is preferably equal to or greater than about 0.12mm and equal to or less than about 0.20 mm, for example.

In addition, each of a dimension of the first inner electrode 11 from anouter edge of the third extending portion 11 c to the first end surface10 e and a dimension of the first inner electrode 11 from an outer edgeof the fourth extending portion 11 d to the second end surface 10 f ispreferably equal to or greater than about 0.04 mm and equal to or lessthan about 0.08 mm, for example.

Hereinafter, another preferred embodiment of the present invention willbe described. In the following description, the same reference numeralswill be given to members with the same or substantially the samefunctions as those in the first preferred embodiment, and thedescriptions thereof will be omitted.

Second Preferred Embodiment

FIGS. 12 and 13 are schematic cross-sectional views of an installationstructure of a multilayer capacitor according to a second preferredembodiment of the present invention. According to the multilayercapacitor 1, the second main surface 10 b and the first and second endsurfaces 10 e and 10 f preferably are concave surfaces, and the firstand second side surfaces 10 c and 10 d preferably are convex surfaces(abbreviated in the figure). Specifically, the second main surface 10 bwhich faces the installation surface 20 a is depressed from the endstoward the center in the length direction L and is depressed from theends toward the center in the width direction W.

Therefore, if all the terminal electrodes 13 to 15 have the same orsubstantially the same thicknesses, a distance between the terminalelectrode 15 and the land 23 positioned at the center in the lengthdirection L becomes longer than a distance between the terminalelectrode 13 and the land 21 and a distance between the terminalelectrode 14 and the land 22. Therefore, there is a concern in that theconnection between the terminal electrode 15 and the land 23 is notreliably established or electrical resistance increases.

According to the multilayer capacitor of the preferred embodiment, theportion of the terminal electrode 15 on the second main surface 10 bwith the largest thickness in the width direction W is thicker than theportions of the first and second terminal electrodes 13 and 14 with thelargest thicknesses in the width direction W. Therefore, the distancebetween the terminal electrode 15 and the land 23 is short. Accordingly,it is possible to reliably connect the terminal electrode 15 to the land23 and to reduce the electrical resistance between the terminalelectrode 15 and the land 23. That is, the multilayer capacitor 1 has anexcellent installation property.

Third Preferred Embodiment

FIG. 14 is a schematic perspective view of a multilayer capacitoraccording to a third preferred embodiment of the present invention.FIGS. 15 to 18 are schematic cross-sectional views of the multilayercapacitor according to the third preferred embodiment.

The first preferred embodiment was described as the example in which theterminal electrodes 16 to 18 were provided on the side of the first mainsurface 10 a in addition to the terminal electrodes 13 to 15. However,the present invention is not limited to that configuration.

As shown in FIGS. 14 to 18, for example, only three terminal electrodes,namely the terminal electrodes 13 to 15 may be provided as terminalelectrodes on the side of the second main surface 10 b.

The first main surface 10 a as an upper surface of the multilayerceramic capacitor 1 is polished such that corner portions of ridgeportions 3 a and 3 b in the length direction L are rounded. Curvatureradii of the ridge portions 3 a and 3 b are preferably equal to or lessthan about 70 μm and are more preferably equal to or greater than about30 μm and equal to or less than about 70 μm, for example.

Portions of unbaked ceramic element assemblies on a side of theinstallation surface 20 a are subjected to barrel polishing for apredetermined period of time in a state of being held by a holder (notshown) until the curvature radii of the ridge portions 3 a and 3 bbecome about 70 μm, for example. Thereafter, sandblast polishing may befurther performed thereon.

Here, a method of determining polishing conditions for the barrelpolishing and the sandblast polishing is not particularly limited.Samples of the ceramic element assemblies may be produced, and thecurvature radii may be measured by the following method. As ameasurement instrument of the curvature radii, KEYENCE digitalmicroscope VHX series can be used, for example.

Portions of the samples on the side of the installation surface (secondmain surface 10 b) are solidified with resin. Thereafter, the ridgeportions 3 a and 3 b are subjected to the barrel polishing and thesandblast polishing for a predetermined period of time.

Then, the polished ridge portions 3 a and 3 b are observed by themeasurement instrument, and start points and end points of the ridgeportions are designated. Thereafter, center points between the startpoints and the end points are designated.

Then, circles which passes through the start points, the center points,and the end points are depicted, and radii of the circles are calculatedas the curvature radii (R amount).

Experimental Example

Multilayer ceramic capacitors with the same or substantially the sameconfiguration as that in the above-described preferred embodiment wereproduced. Then, an experiment for checking adsorption errors andpresence of chipping-off and breakage of the produced sample wasconducted.

The multilayer ceramic capacitors produced as the samples had adimension in the length direction L of equal to or greater than about2.00 mm and equal to or less than about 2.10 mm, a dimension in theheight direction T of equal to or greater than about 0.7 mm and equal toor less than about 1.0 mm, and a dimension in the width direction W ofequal to or greater than about 1.20 mm and equal to or less than about1.40 mm.

The adsorption errors were evaluated by causing the multilayer ceramiccapacitors to be adsorbed by an adsorption nozzle and counting thenumber of multilayer ceramic capacitors which dropped off. The number ofmultiple ceramic capacitors as targets of the adsorption errorevaluation was 10000 for each curvature radius. The results are shown inTable 2.

The presence of chipping-off and breakage was evaluated by counting thenumber of events, in which chipping-off and breakage occurred, bycausing the multilayer ceramic capacitors to be adsorbed by theadsorption nozzle. The number of multiple ceramic capacitors as targetsof the chipping-off and breakage evaluation was 100 for each curvatureradius. The results are shown in Table 2.

TABLE 2 R amount (μm) 20 30 40 50 60 70 80 90 Adsorption errors (numberof 0/10000 0/10000 0/10000 0/10000 0/10000 0/10000 5/10000 7/100000events/number of evaluation targets) Chipping-off and breakage (numberof 5/100 0/100 0/100 0/100 0/100 0/100 0/100 0/100 events/number ofevaluation targets)

According to Table 2, no adsorption error occurred under a condition inwhich the R amount was equal to or greater than about 20 μm and equal toor less than about 70 μm. In contrast, five adsorption errors occurredin a case where the R amount was about 80 μm, and seven adsorptionerrors occurred in a case where the R amount was about 90 μm.

According to Table 2, no chipping-off and breakage occurred under acondition in which the R amount was equal to or greater than about 30 μmand equal to or less than about 90 μm. In contrast, chipping-off andbreakage occurred five times in a case where the R amount was about 20μm.

Therefore, it is possible to avoid occurrence of adsorption errors,chipping-off, and breakage by setting the R amount to be equal to orgreater than about 30 μm and equal to or less than about 70 μm, forexample.

Fourth Preferred Embodiment

FIG. 19 is a schematic perspective view of a multilayer capacitoraccording to a fourth preferred embodiment of the present invention.FIG. 20 is a schematic front view of a second side surface of themultilayer capacitor according to the fourth preferred embodiment. FIG.21 is a schematic cross-sectional view of an installation structure ofthe multilayer capacitor according to the fourth preferred embodiment.FIG. 22 is a schematic cross-sectional view illustrating a process offorming a terminal electrode.

Stress is applied to the multilayer capacitor 1 if the installationboard is bent in the width direction W. The stress applied to themultilayer capacitor 1 easily concentrates at a location between aportion of the outer periphery of the portion 15 a of the signalterminal electrode 15 extending in the thickness direction and the sidesurface 10 c, and a portion of the outer periphery of the portion 15 bof the signal terminal electrode 15 extending in the thickness directionand the side surface 10 d. Therefore, cracking easily occurs in thecapacitor main body 10 from the portion of the signal terminal electrode15 on the capacitor main body 10, which is in contact with the outerperipheries of the portions 15 a, 15 b of the signal terminal electrode15 positioned on the side surfaces 10 c and 10 d, respectively.

As shown in FIGS. 19 and 21, the outer periphery of the portion 15 aincludes a plurality of convex portions 15 a 1 and 15 a 2 which extendfrom a bottom edge of the side surface 10 c toward the first mainsurface 10 a. Therefore, the stress which is applied to the capacitormain body 10 when the installation board is bent is dispersed to theconvex portions 15 a 1 and 15 a 2. Accordingly, it is possible tosignificantly reduce or prevent application of large stress to a singlelocation in the capacitor main body 10. As a result, it is possible toeffectively significantly reduce or prevent occurrence of cracking inthe capacitor main body 10.

From the viewpoint of effectively reducing or preventing an occurrenceof cracking in the capacitor main body 10, the convex portions 15 a 1and 15 a 2 preferably have curved or substantially curved peripherieswhen viewed from the width direction W.

In addition, the terminal electrode 15, in which the outer peripheriesof the portions 15 a and 15 b include the plurality of convex portions15 a 1 and 15 a 2 extending from the bottom edge of the side surface 10c toward the side of the first main surface 10 a, can be manufactured bythe following procedure. As shown in FIG. 22, grooves 41 to 43 whichopen in a surface 40 a of a substrate 40 made of an elastic body such asrubber are filled with conductive paste 45 to form the terminalelectrodes 13 to 15. It is possible to form the terminal electrodes 13to 15 by pressing the capacitor main body 10 against the surface 40 a ofthe substrate 40 in this state. It is possible to form the terminalelectrode 15 including the plurality of convex portions 15 a 1 and 15 a2 by reducing the pressing amount of the capacitor main body 10 againstthe surface 40 a at this time.

In addition, the convex portions 15 a 1 and 15 a 2 can be measured byobserving the side surface 10 c or 10 d of the capacitor main body attwenty-fold magnification by using the measurement microscope MM-60manufactured by Nikon Corporation, for example.

Fifth Preferred Embodiment

FIG. 24 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a fifth preferred embodiment of the presentinvention.

As shown in FIG. 24, the ground terminal electrode is connected to thefirst inner electrodes 11. The ground terminal electrode 13 covers theexposed portion of the extending portion 11 c of each first innerelectrode 11. The portion 13 d of the grounding terminal electrode 13,which is positioned on the second main surface 10 b and covers theexposed portion of the extending portion 11 c, has a thickness whichbecomes thinner toward the outer side portions (both the L(A) side andthe L(B) side) in the length direction L.

The grounding terminal electrode 14 is connected to the first innerelectrodes 11. The grounding terminal electrode 14 covers the exposedportion of the extending portion 11 d of each first inner electrode 11.The portion 14 d of the grounding terminal electrode 14, which ispositioned on the second main surface 10 b and covers the exposedportion of the extending portion 11 d, has a thickness which becomesthinner toward the outer side portions (both the L(A) side and the L(B)side) in the length direction L. In other words, the thickness in thethickness direction T of the portion 14 a is the largest in an area ofits center along the length direction L.

According to the multilayer capacitor 1, the extending portions 11 c and11 d of each inner electrode 11 are overlapped with portions of theterminal electrodes 13 and 14, which are the thickest portions and havean excellent sealing property against moisture, in the length directionL. Therefore, moisture does not easily enter the inner electrodes 11.Accordingly, the multilayer capacitor 1 exhibits excellent moistureresistance.

In order to provide the extending portions 11 c and 11 d such that theextending portions 11 c and 11 d of each inner electrode 11 areoverlapped with the portions of the terminal electrodes 13 and 14, whichare the thickest portions and have the excellent sealing propertyagainst moisture, in the length direction L, it is preferable to arrangethe extending portions 11 c and 11 d at inner side portions to someextent in the length direction L. In such a case, if the innerelectrodes are provided such that edges of the outer side portions ofthe extending portions and the edges of the outer side portions of theeffective portions are linearly positioned as disclosed in JapaneseUnexamined Patent Application Publication No. 2013-46052, an area wherethe inner electrodes face each other decreases. Therefore, there is aproblem in that large capacitance cannot be secured if it is attemptedto improve the moisture resistance in the capacitor disclosed inJapanese Unexamined Patent Application Publication No. 2013-46052.

In contrast, according to the multilayer capacitor 1, the effectiveportion 11A is configured so as to reach the outer side portion (L(A)side) in the length direction L beyond the extending portion 11 c andreach the outer side portion (L(B) side) in the length direction Lbeyond the extending portion 11 d. Therefore, the effective portion 11Ahas a large area. For this reason, the area where the first innerelectrodes 11 and the second inner electrodes 12 face each other islarge in the multilayer capacitor 1. Accordingly, the capacitance of themultilayer capacitor 1 is large. As described above, the multilayercapacitor 1 has a large capacitance and exhibits excellent moistureresistance.

Specifically, it is possible to obtain electrostatic capacitance fromabout 47.0 μF to about 48.0 μF, for example, when a length dimension ofthe capacitor main body 10, in which the grounding terminal electrodes13 and 14 and the signal terminal electrode 15 are provided, is fromabout 2.00 mm to about 2.10 mm, a thickness dimension thereof is fromabout 0.7 mm to about 1.0 mm, and a width dimension thereof is fromabout 1.20 mm to about 1.40 mm, for example.

In addition, it is preferable that a portion of the effective portion11A, which corresponds to a portion extending to a left outer edge inthe length direction L beyond the extending portion 11 c, and at whichthe length direction L perpendicular or substantially perpendicularintersects the thickness direction T, be chamfered and that the lengthfrom the left outer edge of the effective portion 11A on the L(A) sideto a left outer edge of the extending portion 11 c on the L(A) siderange from about 40 μm to about 60 μm, for example. It is preferablethat a portion of the effective portion 11A, which corresponds to aportion extending to a right outer edge in the length direction L beyondthe extending portion 11 d, and at which the length direction Lperpendicularly or substantially perpendicularly intersects thethickness direction T, be chamfered and that the length from the rightouter edge of the effective portion 11A on the L(B) side to the rightouter edge of the extending portion 11 d on the L(B) side range fromabout 40 μm to about 60 μm, for example.

The length from the left outer edge of the effective portion 11A on theL(A) side to the left outer edge of the extending portion 11 c on theL(A) side and the length from the right outer edge of the effectiveportion 11A to the right outer edge of the extending portion 11 d on theL(B) side can be measured by polishing the multilayer capacitor 1 fromthe first side surface 10 c or the second side surface 10 d thereoftoward the center portion thereof and observing the thus-appearing innerelectrode at twenty-fold magnification by using the measurementmicroscope MM-60 manufactured by Nikon Corporation, for example.

In addition, the length dimension, the thickness dimension, and thewidth dimension of the capacitor main body can be measured by using themicrometer MDC-25MX manufactured by Mitutoyo Corporation, for example.In addition, the electrostatic capacitance can be measured by ameasurement instrument HP4268A manufactured by Agilent Technologiesunder conditions of 120 Hz and 0.5 Vrms, for example.

Sixth Preferred Embodiment

FIG. 25 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a sixth preferred embodiment of the presentinvention.

Incidentally, the moisture resistance of the multilayer capacitordepends on how easily moisture can enter the effective portions of theinner electrodes. If moisture can easily enter the effective portions ofthe inner electrodes, the moisture resistance of the multilayercapacitor deteriorates. Therefore, it is necessary to make it difficultfor moisture to enter the effective portions of the inner electrodes inorder to improve the moisture resistance of the multilayer capacitor. Asa method of making it difficult for moisture to enter the effectiveportions, a method of extending the lengths in the thickness direction Tof the extending portions can be considered. However, since the areas ofthe effective portion decrease if the lengths of the extending portionsare extended, capacitance tends to decrease.

According to the multilayer capacitor 1, the first and second effectiveportions 11A and 12A respectively have portions which extend toward thesecond main surface 10 b beyond or below upper edges of the extendingportions 11 c, 11 d, and 12 b connected to the main bodies of therespective electrodes 11 and 12, and located between the extendingportions 11 c and 11 d in the length direction. In other words, aminimum distance between the first effective portion 11A and the secondmain surface 10 b is shorter than all of three lengths in the thicknessdirection T, the length of the portion 11 c, the length of the portion11 d, and the length of the portion 12 b. And the minimum distancebetween the second effective portion 12A and the second main surface 10b is shorter than all of three lengths in the thickness direction T, thelength of the portion 11 c, the length of the portion 11 d, and thelength of the portion 12 b. For this reason, it is possible to increasethe area where the first effective portion 11A and the second effectiveportion 12A face each other while significantly reducing or preventingdeterioration in the moisture resistance by securing the lengths of theextending portions 11 c, 11 d, and 12 b and to thus increase thecapacitance.

Specifically, the first effective portion 11A includes first projectingportions 11A1 and 11A2, which project toward the second main surface 10b, in a region where the extending portions 11 c, 11 d, and 12 b are notprovided in the length direction L when viewed from the width directionW as shown in FIGS. 25 and 26 such that a minimum distance in thethickness direction between the first effective portion 11A and thesecond main surface 10 b is shorter than dimensions of the extendingportions 11 c and 11 d. The second effective portion 12A includes secondprojecting portions 12A1 and 12A2, which project toward the second mainsurface 10 b, in a region where the extending portions 11 c, 11 d, and12 b are not provided in the length direction L when viewed from thewidth direction W such that a minimum distance in the thicknessdirection between the second effective portion 12A and the second mainsurface 10 b is shorter than a dimension in the thickness direction ofthe extending portion 12 b. The first projecting portion 11A1 and thesecond projecting portion 12A1 face each other in the width direction W.The first projecting portion 11A2 and the second projecting portion 12A2face each other in the width direction W. Therefore, the capacitanceincreases by an amount corresponding to the first projecting portions11A1 and 11A2 and the second projecting portions 12A1 and 12A2. Thelengths of the extending portions 11 c, 11 d, and 12 b preferably arethe same or substantially the same as those in a case where the firstprojecting portions 11A1 and 11A2 and the second projecting portions12A1 and 12A2 are not provided. Therefore, the moisture resistance doesnot deteriorate.

In addition, the lengths of the first projecting portions 11A1 and 11A2and the second projecting portions 12A1 and 12A2 in the thicknessdirection T are preferably equal to or greater than about 0.003 mm andequal to or less than about 0.007 mm, for example.

In addition, shapes of the first and second effective portions 11A and12A can be checked by observing the first and second effective portions11A and 12A, which appear by polishing the multilayer ceramic capacitor1 from the first side surface or the second side surface in the widthdirection, at twenty-fold magnification by using the measurementmicroscope MM-60 manufactured by Nikon Corporation, for example.

Seventh Preferred Embodiment

FIGS. 27 and 28 are schematic cross-sectional views of a multilayercapacitor according to a seventh preferred embodiment of the presentinvention.

As shown in FIGS. 27 and 28, G1 represents a distance between theeffective portions 11A and 12A and the second main surface 10 b, and G2represents a distance between the effective portions 11A and 12A and thefirst main surface 10 a. According to the present preferred embodiment,G1 is shorter than G2. For this reason, chipping-off and breakage do noteasily occur even if impact is applied to the first main surface 10 a orridge portions, corner portions, and the like adjacent to the first mainsurface 10 a in the multilayer capacitor main body 10. Accordingly, itis possible to improve reliability of the multilayer ceramic capacitor1.

In addition, G1 is preferably equal to or greater than about 0.049 mmand equal to or less than about 0.055 mm, and G2 is preferably equal toor greater than about 0.056 mm and equal to or less than about 0.063 mm,for example.

Eighth Preferred Embodiment

FIG. 29 is a schematic back view of a multilayer ceramic capacitoraccording to an eighth preferred embodiment of the present invention. Asshown in FIG. 29, a dimension of the extending portion 12 b in thelength direction L is the largest at an area of a center or approximatecenter of the second main surface 10 b in the width direction W andbecomes smaller toward the outer side portions in the width direction W.For this reason, the equivalent series inductance (ESL) is made uniformand is significantly reduced. In addition, the dimension of theextending portion 12 b in the length direction L may differ at thecenter of the second main surface 10 b in the width direction W and atthe ends of the outer side portions by about 40 μm, for example.

A dimension of the extending portion 11 c preferably is the smallest ata portion of the extending portion 11 c from the center to the first endsurface 10 e in the width direction W and is the largest at a portion ofthe extending portion 11 c from the outer edge thereof to the first endsurface 10 e in the width direction W. In addition, a dimension of theextending portion 11 d preferably is the smallest at a portion of theextending portion 11 d from the center to the second end surface 10 f inthe width direction W and is the largest at a portion of the extendingportion 11 d from the outer edge thereof to the second end surface 10 fin the width direction W. Also, a distance in the length direction Lbetween the first end surface 10 e and the extending portion 11 c at acenter or approximate center of the second main surface 10 b in thewidth direction W is smaller than each distance in the length directionL between the first end surface 10 e and the extending portion 11 cnearest to the first and second side surfaces 10 c, 10 d. Also, adistance in the length direction L between the second end surface 10 fand the extending portion 11 d at a center or approximate center of thesecond main surface 10 b in the width direction W is smaller than eachdistance in the length direction L between the second end surface 10 fand the extending portion 11 d nearest to the first and second sidesurfaces 10 c, 10 d. Therefore, cracking does not easily occur in anouter layer portion of the ceramic element assembly 10 in the thicknessdirection W.

In addition, each of a dimension of the extending portion 11 c from thecenter thereof to the first end surface 10 e in the width direction Wand a dimension of the extending portion 11 d from the center thereof tothe second end surface 10 f in the width direction W is preferably equalto or greater than about 0.085 mm and equal to or less than 0.097 mm,and each a dimension of the extending portion 11 c from the outer edgethereof to the first end surface 10 e in the width direction W and adimension of the extending portion 11 d from the outer edge thereof tothe second end surface 10 f in the width direction W is preferably equalto or greater than about 0.098 mm and equal to or less than about 0.140mm, for example.

Ninth Preferred Embodiment

FIG. 30 is a schematic cross-sectional view of an installation structureof a multilayer capacitor according to a ninth preferred embodiment ofthe present invention. In the description of the present preferredembodiment, FIGS. 1 to 9 will be referred to in the same manner as inthe first preferred embodiment.

According to the present preferred embodiment, lengths of the portions15 a and 15 b, which are shown in FIGS. 1 and 2, at the ridge portionsof the multilayer capacitor main body 10 in the length direction L arelonger than a length of the portion 15 c, which is shown in FIG. 9, inthe length direction L. Similarly, lengths of the portions 13 a and 13b, which are shown in FIGS. 1 and 2, at the ridge portions of themultilayer capacitor main body 10 in the length direction L are longerthan a length of the portion 13 d, which is shown in FIG. 9, in thelength direction L. Lengths of portions 14 a and 14 b, which are shownin FIGS. 1 and 2, at the ridge portions of the multilayer capacitor mainbody 10 in the length direction L are longer than a length of theportion 14 d, which is shown in FIG. 9, in the length direction L.Therefore, it is possible to increase an amount of wetting of solderwhich configures a joining material 30 as compared with a case shown inFIG. 31, in which dimensions of the portions 15 c, 13 c, and 14 d in thelength direction L are short, for example. Accordingly, it is possibleto reduce a total area which the multilayer ceramic capacitor and thejoining material 30 occupy while securing strong fixing force of themultilayer ceramic capacitor with respect to the installation board 20.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer capacitor comprising: a multilayercapacitor main body which includes first and second main surfaces, firstand second side surfaces, and first and second end surfaces, the firstand second main surfaces extending in a length direction and a widthdirection, the first and second side surfaces extending in the lengthdirection and a thickness direction, and the first and second endsurfaces extending in the width direction and the thickness direction; afirst inner electrode extending in the length direction and thethickness direction and including a first effective portion, a firstextending portion, and a second extending portion, the first extendingportion being connected to the first effective portion and extending tothe second main surface, and the second extending portion beingconnected to the first effective portion and extending to the secondmain surface; a second inner electrode extending in the length directionand the thickness direction and including a second effective portion anda third extending portion, the second effective portion facing the firsteffective portion in the width direction, and the third extendingportion being connected to the second effective portion, not facing thefirst inner electrode, and extending to the second main surface; a firstterminal electrode which is connected to an exposed portion of the firstextending portion and extends across a portion of the second mainsurface on a side of the first end surface in the length direction, thefirst end surface, and the first and second side surfaces; a secondterminal electrode which is connected to an exposed portion of thesecond extending portion and extends across a portion of the second mainsurface on a side of the second end surface in the length direction, thesecond end surface, and the first and second side surfaces; and a thirdterminal electrode which is connected to an exposed portion of the thirdextending portion and extends across a portion of the second mainsurface between the first terminal electrode and the second terminalelectrode in the length direction and the first and second sidesurfaces; wherein a distance in the thickness direction between thefirst effective portion and the second main surface is shorter than adistance in the thickness direction between the first effective portionand the first main surface; a distance in the thickness directionbetween the second effective portion and the second main surface isshorter than a distance in the thickness direction between the secondeffective portion and the first main surface; a distance in the lengthdirection between the first end surface and the first extending portionat a center or approximate center of the second main surface in thewidth direction is smaller than each distance in the length directionbetween the first end surface and the first extending portion nearest tothe first and second side surfaces; and a distance in the lengthdirection between the second end surface and the second extendingportion at the center or approximate center of the second main surfacein the width direction is smaller than each distance in the lengthdirection between the second end surface and the second extendingportion nearest to the first and second side surfaces.
 2. The multilayercapacitor according to claim 1, wherein; the first effective portionincludes a first projecting portion which projects toward the secondmain surface, and a minimum distance in the thickness direction betweenthe first projecting portion and the second main surface is shorter thandimensions of the first and second extending portions; and the secondeffective portion includes a second projecting portion which projectstoward the second main surface, and a minimum distance in the thicknessdirection between the second projecting portion and the second mainsurface is shorter than a dimension in the thickness direction of thethird extending portion.
 3. The multilayer capacitor according to claim1, wherein a dimension of the third terminal electrode on the secondmain surface in the length direction is greater than a dimension of thefirst and second terminal electrodes on the second main surface in thelength direction.
 4. The multilayer capacitor according to claim 1,wherein the first and second terminal electrodes extend across thesecond main surface from a first end to a second end in the widthdirection and have a thickest portion at a portion on a side of thefirst end beyond a center portion of the second main surface in thewidth direction.
 5. The multilayer capacitor according to claim 4,wherein the thickest portion projects toward the center portion in thelength direction.
 6. The multilayer capacitor according to claim 1,wherein L1 represents a dimension of the exposed portion of the firstextending portion in the length direction; L2 represents a dimension ofthe exposed portion of the second extending portion in the lengthdirection; and L3 represents a dimension of the exposed portion of thethird extending portion in the length direction; whereinL3>L1 andL3>L2 are satisfied.
 7. The multilayer capacitor according to claim 1,wherein the first main surface does not contain any terminal electrodesthereon.
 8. The multilayer capacitor according to claim 2, wherein thefirst main surface does not contain any terminal electrodes thereon. 9.The multilayer capacitor according to claim 3, wherein the first mainsurface does not contain any terminal electrodes thereon.
 10. Themultilayer capacitor according to claim 4, wherein the first mainsurface does not contain any terminal electrodes thereon.
 11. Themultilayer capacitor according to claim 5, wherein the first mainsurface does not contain any terminal electrodes thereon.
 12. Themultilayer capacitor according to claim 6, wherein the first mainsurface does not contain any terminal electrodes thereon.